Cellular intumescent materials

Abstract

A cellular intumescent material comprising a substantially open-called substrate impregnated with a flexible intumescent polymer. The open-celled nature of the substrate is retained. The substrate may be a latex or urethane-based foam, a natural rubber or a synthetic rubber. The impregnant comprises at least a binder (A) and an intumescent component (B). The binder (A) can be a polyester, a liquid polymer system, a resin, a latex or an elastomer solution. The intumescent component (B) consists of a carbonific element (e.g. starch, sugar, sorbitol or pentaerythritol, or a compound which can polymerize to a "ladder" structure) and a spumific element (e.g. an inorganic acid or a precursor therefor). On exposure to a flame the materials flame initially but form a protective char and subsequently extinguish. The char prevents further burning of the treated material.

Having now described my invention, what I claim is: 
     
       1. A cellular, intumescent material obtained by treating an open-celled substrate selected from the class consisting of polyether-based urethane foams, latex foams, natural rubbers and synthetic rubbers with a flexible, intumescable polymeric material, said flexible, intumescable polymeric material being one which, on exposure to a flame, melts, foams and solidifies to a foamed carbonaceous char, whereby said open-celled substrate becomes surrounded with an intumescent foam layer, said intumescable polymeric material comprising (A) a binder and (B) an intumescent component, said intumescent component (B) comprising a carbonific element different from said binder (A) and a spumific element. 
     
     
       2. The material of claim 1, wherein said substrate is a synthetic rubber selected from the class consisting of polybutadiene and styrene/butadiene rubbers. 
     
     
       3. The material of claim 1, wherein said binder (A) is a substance selected from the class consisting of polyesters, liquid polymer systems, resins, latices and solutions of thermoplastic elastomeric materials. 
     
     
       4. The material of claim 3, wherein said binder (A) is a substance selected from the class consisting of butadiene, styrene/butadiene copolymers and acrylonitrile/butadiene copolymers. 
     
     
       5. The material of claim 3, wherein said binder (A) is a substance selected from the class consisting of phenolic resins, urea/formaldehyde resins, resins based on polyvinyl chloride, alkyd resins and polyamide resins. 
     
     
       6. The material of claim 3, wherein said binder (A) is a substance selected from the class consisting of latices of neoprene, of styrene/butadiene rubber, of polyvinyl acetate, of polyvinyl chloride and of polyacrylonitrile. 
     
     
       7. The material of claim 1, wherein said carbonific element is a polyhydric material of high carbon content. 
     
     
       8. The material of claim 1, wherein said carbonific element is an aromatic compound capable of polymerisation to a "ladder" structure. 
     
     
       9. The material of claim 7, wherein said carbonific element is a substance selected from the class consisting of sorbitol, pentaerythritol and starch. 
     
     
       10. The material of claim 8, wherein said carbonific element is a substance selected from the class consisting or ortho- and para-nitroaniline. 
     
     
       11. The material of claim 1, wherein said spumific element is a substance selected from the class consisting of inorganic acids and substances capable of decomposition to yield inorganic acids. 
     
     
       12. The material of claim 11, wherein said spumific element is a substance selected from the class consisting of boric acid, phosphoric acid, sulphuric acid, ammonium halides, ammonium phosphates ammonium polyphosphates, melamine phosphate, urea phosphate and para-nitroaniline bisulphate. 
     
     
       13. A cellular, intumescent material consisting essentially of (a) an open-celled substrate selected from the class consisting of polyether-based urethane foams, latex foams, natural rubbers and synthetic rubbers, and   (b) a flexible intumescable polymeric material, said flexible intumescable polymeric material being one which, on exposure to flame, melts, foams and solidifies to a foamed carbonaceous char, whereby said open-celled substrate becomes surrounded with an intumescent foam layer, said intumescable polymeric material comprising; (A) a binder, and   (B) an intumescent component, said intumescent component (B) comprising: (i) a carbonific element different from said binder (A) and   (ii) a spumific element; wherein said cellular intumescent material is obtained by treating said open-celled substrate with said flexible, intumescable polymeric material.